Allometric Equation for Aboveground biomass estimation of selected indigenous tree speciesrnnamely, Balanites aegyptiaca, Piliostigma thonningii, Terminalia macropetra, and Vitellariarnparadoxa was conducted in Gambella National Park, Southwestern Ethiopia. The allometricrnequation that was obtained for the four species had significant (P< 0.000) fit for linear model.rnSelection of fourty-eight (48) tree sampled numbers based on their Diameter at Breast Heightrn(DBH) and height distribution using preferential sampling. The selection of the best model wasrnbased on lowest AIC, RSE and P values and highest R2.The best model for predicting abovernground biomass for Balanites aegyptiaca, model 6, Ln(AGB= -4.5429+2.7029 ln(DBH) +rn0.7704ln(H)+0.2702ln(Ï ) having adjusted R2=0.97and p-value of 2.554X10-07.For Piliostigmarnthonningii, model 9,Ln (AGB)=-1.9544 + 2.8207ln(DBH) +0.2358ln(H)was best model with,rnadjusted R2=0.964 and p-value of 1.861X10-08.. Similarly, for Terminalia macroptera, model-rn15, Ln(AGB)=-5.8474+ 3.4216ln(DBH)+0.4712ln(H)+ 0.2261ln(Ï), with adjusted R2=0.985rnand p-value of 0.0006379 and for Vitellaria paradoxa, model 20, Ln(AGB= -rn8.6865+5.1368ln(DBH) + 0.6006 ln(Ï)+ 0.9559ln(H) was the best model with ,adjustedrnR2=0.981and p-value of 0.0003608. The models fit regression of all selected species and R2 werern> 80%. Comparison of these results with those obtained using generalized allometric modelrnrevealed differences with biomass estimation. The results ofthis studyor the newly proposedrnallometric models also significantly improved the estimation accuracy as compared to thernprevious developed equations.